Control



Jan. 25, 1938. K. P. BRACE 2,106,450

CONTROL Filed Aug. 21, 1956 so /2 Z2 5 4 /6 I .32 I [I 1 INVENTOR.KEMPEPP fi/mczr BY mt *f M ATTORNEYS Patented Jan. 25, 1938 UNITEDSTATES PATENT OFFICE CONTROL Application August 21, 1936, Serial No.97,102

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This invention relates to controls, and is illustrated as embodied in athermostatically-actuated mechanism for operating a switch or theequivalent.

An object of the invention is to provide a sensitive operating mechanismwhich can easily be adjusted. It is diflicult to adjust controlmechanisms of this type when they are actuated by the expansion of afluid against the inherent resistance of a metallic bellows on which thefluid acts, such adjustments involving changes in the mounting of thebellows, and being afiected by difierent characteristics of differentbellows. It is extremely diflicult to make such bellows withcharacteristics which are even approximately uniform.

According to the present invention, a lever or the like which actuatesthe switch is engaged by a'metallic expansible chamber (such as a wafermade up by uniting the margins of two metal disks) which is deliberatelymade up to have relatively little resilience.

The yielding resistance is supplied by means such as a leaf springsecured to and extending from the end of the lever. This spring isflexed by the expanding fluid against a stop such as a setscrewadjustably threaded into a bracket or the like adjacent the end of thespring. The device is readily adjusted by changing the setting of thisstop.

The above and other objects and features of the invention, includingvarious novel arrangements and desirable constructions, will be apparentfrom the following description of the i1- lustrative embodiment shown inthe accompanying drawing, in which:

The figure is a side elevation of the control, with the expansiblechamber broken away in section.

In the illustrated arrangement, a suitable base II] has mounted thereona switch H, of any desired type, shown as actuated by a plunger H. Theplunger I4 is engaged by a vertical part l6, having a relatively shortthrow, of a bellcrank lever having a horizontal arm l8, and fulcrumed ona pivot 20 carried by the base Ill.

The arm 18 has an upwardly-oifset portion 22 engaged by an expansiblechamber 24, deliberately constructed to have relatively littleresilience, and containing the usual volatile expanding operating fluid.If the entire device is mounted at the point whose temperature is tocontrol the switch, the chamber 24 vmay be sealed; or if there is to bea control from some remote point, the chamber may be connected by aconduit 26 with a bulb or the like at the point whose temperature is tocontrol the switch l2. part 24 may be made by soldering or welding orotherwise securing together the margins of two disks, preferably oflight-gauge metal.

A leaf spring 28 is riveted or otherwise secured to the end of the leverI6l8-22, to form an extension thereof. Springs of this character arereadily made with substantially uniform characteristics. The end of thisspring bears against an adjustable stop such as a setscrew 30 threadedthrough a bracket 32 mounted on the base l0. Thus expansion of theoperating fluid flexes the spring 28 against the stop 30, and the deviceis readily adjusted by changing the setting of this stop.

As the arm l822, plus the spring 28, forms a very long lever arm, theadjustment is very sen- U sltive. This is important, as the expansion ofthe device 24 which actuates the switch is a very small amount,necessitating extremely accurate setting of the resistance against which0 it operates.

While one illustrative embodiment has been described in detail, it isnot my intention to limit the scope of my invention to that embodiment,or otherwise than by the terms of the appended claims.

I claim:

1. A thermostatic control or the like comprising a switch, a pivotedlever having on one side of its pivot a part with a relatively smallthrow arranged to actuate said switch, an expansible 30 chamber engagingsaid lever on the other side of the pivot from said part and containingan operating fluid and having relatively little inherent resilience, aleaf spring secured to and forming an extension from the end of saidlever 35 on the other side of the pivot from said part, and anadjustable stop engaging the spring some distance beyond the end of thelever and against which the spring is flexed by expansion of saidchamber by the fluid. 40

2. A thermostatic control or the like comprising a switch, a pivotedlever having on one side of its pivot a part with a relatively smallthrow arranged to actuate said switch, an expansible chamber engagingsaid lever on the other side '45 of the pivot from said part andcontaining an operating fluid and having relatively little inherentresilience, a leaf spring secured to and forming an extension from theend of said lever on the other side of the pivot from said part, a 50bracket adjacent the end of the spring, and an adjustable setscrewthreaded into said bracket and engaging the spring some distance beyondthe end of the lever and against which the spring is flexed by expansionof said chamber by the fluid.

KEMPER P. BRACE.

